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Investigating ocean deoxygenation during the PETM through the Cr isotopic signature of foraminifera

Remmelzwaal, Serginio R.C.; Dixon, Sophie; Parkinson, Ian J.; Schmidt, Daniela N.; Monteiro, Fanny M.; Sexton, Philip; Fehr, Manuela A.; Peacock, Caroline; Donnadieu, Yannick and James, Rachael H. (2019). Investigating ocean deoxygenation during the PETM through the Cr isotopic signature of foraminifera. Paleoceanography and Paleoclimatology, 34(6) pp. 917–929.

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DOI (Digital Object Identifier) Link: https://doi.org/10.1029/2018pa003372
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Abstract

Over the past several decades, oxygen minimum zones have rapidly expanded due to rising temperatures raising concerns about the impacts of future climate change. One way to better understand the drivers behind this expansion is to evaluate the links between climate and seawater deoxygenation in the past especially in times of geologically abrupt climate change such as the Palaeocene-Eocene Thermal Maximum (PETM), a well characterised period of rapid warming ~56 million years ago. We have developed and applied the novel redox proxies of foraminiferal Cr isotopes(δ53Cr) and Ce anomalies (Ce/Ce*) to assess changes in paleo-redox conditions arising from changes in oxygen availability. Both δ53Cr and Cr concentrations decrease notably over the PETM at intermediate to upper abyssal water depths,indicative of widespread reductions in dissolved oxygen concentrations. An apparent correlation between the sizes of δ53Cr and benthic δ18O excursions during the PETM suggests temperature is one of the main controlling factors of deoxygenation in the open ocean. ODP Sites 1210 in the Pacific and 1263 in the Southeast Atlantic suggest that deoxygenation is associated with warming and circulation changes, as supported by Ce/Ce* data. Our geochemical data are supported by simulations from an intermediate complexity climate model (cGENIE), which show that during the PETM anoxia was mostly restricted to the Tethys Sea, while hypoxia was more widespread as a result of increasing atmospheric CO2 (from 1 to 6 times pre-industrial values).

Item Type: Journal Item
Copyright Holders: 2019 American Geophysical Union
ISSN: 1944-9186
Keywords: Chromium; Cerium; Deoxygenation; Foraminifera; Hypoxia; PETM
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 61099
SWORD Depositor: Jisc Publications-Router
Depositing User: Jisc Publications-Router
Date Deposited: 13 May 2019 08:15
Last Modified: 20 Jan 2020 21:55
URI: http://oro.open.ac.uk/id/eprint/61099
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